74 lines
2.5 KiB
Markdown
74 lines
2.5 KiB
Markdown
# Grains
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Calculate the number of grains of wheat on a chessboard given that the number
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on each square doubles.
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There once was a wise servant who saved the life of a prince. The king
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promised to pay whatever the servant could dream up. Knowing that the
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king loved chess, the servant told the king he would like to have grains
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of wheat. One grain on the first square of a chess board, with the number
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of grains doubling on each successive square.
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There are 64 squares on a chessboard (where square 1 has one grain, square 2 has two grains, and so on).
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Write code that shows:
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- how many grains were on a given square, and
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- the total number of grains on the chessboard
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## For bonus points
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Did you get the tests passing and the code clean? If you want to, these
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are some additional things you could try:
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- Optimize for speed.
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- Optimize for readability.
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Then please share your thoughts in a comment on the submission. Did this
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experiment make the code better? Worse? Did you learn anything from it?
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Run the tests with:
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```bash
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bats grains_test.sh
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```
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After the first test(s) pass, continue by commenting out or removing the
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`[[ $BATS_RUN_SKIPPED == true ]] || skip`
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annotations prepending other tests.
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To run all tests, including the ones with `skip` annotations, run:
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```bash
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BATS_RUN_SKIPPED=true bats grains_test.sh
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```
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## Source
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JavaRanch Cattle Drive, exercise 6 [http://www.javaranch.com/grains.jsp](http://www.javaranch.com/grains.jsp)
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## External utilities
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`Bash` is a language to write "scripts" -- programs that can call
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external tools, such as
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[`sed`](https://www.gnu.org/software/sed/),
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[`awk`](https://www.gnu.org/software/gawk/),
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[`date`](https://www.gnu.org/software/coreutils/manual/html_node/date-invocation.html)
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and even programs written in other programming languages,
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like [`Python`](https://www.python.org/).
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This track does not restrict the usage of these utilities, and as long
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as your solution is portable between systems and does not require
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installation of third party applications, feel free to use them to solve
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the exercise.
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For an extra challenge, if you would like to have a better understanding
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of the language, try to re-implement the solution in pure `Bash`,
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without using any external tools. Note that there are some types of
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problems that bash cannot solve, such as performing floating point
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arithmetic and manipulating dates: for those, you must call out to an
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external tool.
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## Submitting Incomplete Solutions
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It's possible to submit an incomplete solution so you can see how others
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have completed the exercise.
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